petroholic: yep, pretty much it. you only need to back your mechanical advance off enough to prevent pinging, if present, as vacuum advance only applies to part-throttle operation. the old "32-36 degrees at 3000" rule still applies, and the vacuum can won't affect that. all this assumes you're running 93 octane.
you only need the can if you have low idle vacuum, particularly in gear. most stock style hei cans and even the msd cans are designed to work with 15 inches of vacuum at idle, so while running the low vacuum can won't hurt you, you may not need it.